The most efficient settings for the 1070 ti (NOT THE 1070) put the TDP at about 104 watts (slightly under 60%), which is only 416 watts.
 My 5-card "mix of 1070/1070ti/1080" rigs run all the cards in the 104-110 watt range and only pull 700 watts AT THE WALL despite using somewhat power hungry AMD 8320e CPUs for the most part - which is going to be more like 640 watts out of the PS itself (I do run them on Seasonic X-850 PS for the most part, one on a SS-860, as those have enough CONNECTIONS that I don't need to use splitters - but from a "handle the power" standpoint the EVGA G2/P2/T2 series would be fine).

 A 750 should easily handle an entire 4 card rig if running the cards at EFFICIENT settings, much less splitting an 8-card rig between 2 of the PS.

 Don't run the SSD on a power supply seperate from the MB - power draw is too low and too likely to do ground loops.
 Fans on the second PS make perfect sense.